Pump piston



Nov. 29, 1932. c. LAMB 1,889,178

, PUMP PISTON Filed Aug. 4,1950

A 7" roe/v5 y ramieduemaaiesz CHARLES LAMB, F LOB ANGELES, OALIIGENlia r if m rrsron Application rues august a, 1930. semi at. tracer of abrasive materials. Because of the high F pressurerequired and the large content of abrasive materials carried by the rotary fluid, the wear on the pistons of the slush pumps is very great so t at after a short period of operation it is necessary to mechanically adjust the piston into proper contact with its cylinder wall. y It is an object of my invention to provide a piston which is self-adjusting and Will auto matically be maintained in proper contact ates.

In accordance with this purpose I have pro- Vided a pump piston formed of a resilient material, such as rubber, with end plates which are adapted to exert an axial pressure on the ends of the piston to expand it radially into the desired working contact with the wall of the cylinder. T

It the contact between the ends oi the piston and the cylinder Wallis such that there is no leakage of the fluid, there is but little wear on the middle part of the piston. In order to establish such a contact I provide a iston body of resilient material having an por- 40 tions which are retained in proper working contact with the cylinder by the fluid pressure within the cylinder.

If the fluid in such pumps is permitted to come into contact with the ends of the piston vformed of resilient material, I have'found that the ends of the piston are rapidly worn J away.

It is an object of this invention to provide a pump piston in which the resilient body willv be protected from direct contact with the fluid being pumped and consequently from v with the wall of the cylinder which it operthef reater part of the abrasive action of the flui I have found that it the movement of the end plates toward each other to accomplish the desired radial expansion of the piston body is restricted only by the inherent resistance to deformation of the resilient body it is possible for the piston body to be so expanded radially by the pressure on its ends that it becomes frozen in the cylinder. m

It is a further objectof this invention to provide a pump piston of the class described having means for limiting the movement of the end plates toward each other and thus limiting the axial pressure on and radial expansion of the piston body. 7

Other objects and advantages will be pointed out in the following description in which reference will be had to the accom= panying drawing.

In the accompanying drawing, in which a preferred and an alternative form of my invention are illustrated:

Fig. 1 is an elevational View.

Fig. 2 is a cross-section of the preferred form of the piston of myinvention installed in a pump cylinder. 7

Fig. 3 is a cross-section of the alternative form of the piston of my invention installed in a pump cylinder Fig. 4 is a sectional View taken as illue 'trated on the line 4-4 of Fig. 3.

Referring in detail to the drawing and particularly to Fig. 1, the numeral 11 indicates the resilient piston body of the piston 12 of my invention. The body 11 is preferably formed of rubber or rubber composition having good wearing qualities. A central por tion 13 of the piston body 11 is cylindrical and of such a diameter that this portion-pf the piston body may be slidably disposed in the cylinder in which it is adapted to operate without deformation. The diameter of'the piston body 11 at each of its ends is slightly greater than the diameter of the central portion 13 so that a lip 14 is formed at each end of the piston body 11 of such a diameter as to require some deformation when the piston 12 is installed inja cylinder.

As best shown in Fig. 2, the preferred form of my invention is provided with a central cylindrical bore of a diameter somewhat larger than the diameter of a reduced portion 16 of a piston rod 17 upon which the piston I 12 of'my invention is adapted to be installed. Formed in each'endof the piston body 11 is an. inner concentric annular channel 18 an outer hub portion 22. The ub portion 22' of the end plate 20 is adapted to abut against a shoulder 23, separating the reduced portion 16 from the remainder of the piston rod 17, and the hub portion 22 of the end plate 21 is adapted to be engaged by a nut 24 which is screwed onto a threaded end 25 of the reduced portion 16 of the piston rod 17.

Each of the end plates 20 and 21 has an inner surface 26 adapted to engage end faces 27 of the piston body 11. Projecting inwardly from the inner surface 26 of each of the end plates 20 and 21 is a compressing means in the form of an inner concentric annular flange 28. The annular flanges 28 are adapted to be received in the channels 18 formed in each end of the piston body 11. As will be seen by reference to Fig. 2 of the drawing, the channel 18 and the cooperating flange 28 incline outwardly toward the center of the piston body 11 to a slight extent so that as the end plate 21 is moved toward the end plate 20 the flange 28 will exert a pressure upon that portion of the piston body 11 between the channel 18 and the central bore 15 tending to clamp the piston body 11seeurely in place. Also formed on the inner surface 26 of each of the end plates 20 and 21 at the outer periphery thereof is an outer inwardly extending concentric annular flange 29 which is received in the outer channel 19. The flange 29 contacts only the inner surface 30 of the channel 19 so that the outer surface 31 of the channel 19 is exposed-to contact the fluid contained within the cylinder 32.

In the preferred form of my invention, illustrated in Fig. 2, each of the end plates 20 and 21 is provided with a hollow cylindrical inwardly extending sleeve 33. The inner diameter of the hollow sleeves 33 is such that the end plates 20 and 21 may be slidablv disposed upon the reduced portion 16 of the piston rod 17. The outer diameter of the sleeves 33 is such that the piston body 11 may be slidably positioned thereon. The

, sleeves 33 are made of such a length that when their inner ends contact each other the pressure exerted upon the end' surfaces 27 of the piston body 11 by the end plates 20 and 21 will be great enough to cause the piston body 11 to be radially expanded into working contact with the wall of the cylinder 32 but not great enough so that thisv radial ex pansion will be sufiicient to cause the piston body 11 to become frozen and immovable in the cylinder 32.

The end plates 20 and 21 are installed upon the reduced portion 16 of the piston rod 17 with the piston body 11 positioned upon the sleeves 33 between the end lates 20 and 21, and the piston 12 is instal ed in the cylinder 32. Since the end lips 11 are under compression when installed in the cylinder 32, as previously explained, no fluid pressure exists between the said lips and the said cylinder. The fluid pressure on the exposed end of the piston body 11 forces the lips 14 into a fluid tight contact with the cylinder wall 32 thus preventing the abrasive content of the fluid being pumped from entering between the cylinder Wall 32 and the piston body 14 and wearing the piston body 14. As the end plate 21 is moved toward the end plate 20 by screwing the nut 24 upon the threaded end 25 of the reduced portion 16 of the piston rod 17. the piston body 11 is subjected to axial pressure, which causes its radial expansion. The radial expansion ofthe piston body 11 causes the central portion 13 of the piston body 11 to be moved into working contact with the wall of the cylinder 32. \Vhen the desired radial expansion has been secured, a lock nut- 34 is screwed onto the threaded end 25 of the piston rod 17 to hold the nut 24 in place. As the piston body 11 becomes worm it is possible to screw the nut 24 further upon the ,piston rod 17 so that the piston body 11 is subjected to a greater axial pressure and consequent radial expansion. The possibility that the radial expansion of the piston body resulting fromthe movement of the end plate 21 toward the end plate 20 may be such that the piston body 11 will become frozen in the cylinder 32 is obviated'by the action of the sleeves 33 which contact each other and prevent further movement of the end plate 21 toward the end plate 20 before such excessive radial expansion is effected.

In that form of embodiment of my invention illustrated in Fig. 3, the form of the piston body 11 of resilient material differs from the form of the piston body 11 illustrated in Fig. 2 only in that the central cylindrical bore 35 of the piston body 11 is smaller. this bore 35 being adapted to permit the piston body 11 to be positioned directly upon the reduced portion 16 of the piston rod 17. The end plates 20-and 21 in this embodiment of my invention are exactly like the end plates 20 and 21. as illustrated in Fig. 2, with the exception that there are no sleeves 33 provided.

, ac against the nut 2d to holdit no its The rods 36 are a len h somewhat less thag l that/of the piston bo y 11, as illustrated in i. 3

threaded end 25 of the piston rod 17 the end late 21 is moved toward the end plate 20.

is movement of the end plate 21 toward the end ate will be limited either by the contact tween the end lates and the rods 36, or by the incompressi ility of those elements of thepiston body 11 represented by 8 the dotted lines 37 as being a continuation of the rods 36, depending upon the relative length of the rods 36 and the piston body 11. In that form of embodiment hereinbefore described the not 2% is advanced on the l 'threaded end 25 of the piston rod 17 until the desired contact hetwecn the piston hodv ill and the wall of the cylinder 32 is secured, nt which time the look not 34 is advanced on the threaded end 25 of the piston rod 17 proper position. v

l claim as my invention: 1. In combination: a resilient piston body heving end lips surrounding annular chan- 8 nels, and having a central opening through which a shaft may extend; metal end plates adapted to pressurally engage the ends of said resilient piston hody; and rods supported in said body to limit the pressure exerted ltd on said body by sold end plates.

2. in combination: n resilient piston body hoving a control opening through which a piston rod may extend, the opposite end wells of said body having a concentric channel defining on peripherol li end pistes adopted to pressnrelly on age is e ends oi: ssid resilient piston hody, eaci oi said end pistes honing aconcentric flange extending inwordly into sold channel leaving a portion m off said evailnhle for occupation by 'dnidnnder ressnre to force said peripheral hp t o wall. of the cylinder in which sold piston body is adopted to operate; means for moving one of said end plates toh word the other to compress and radiellp enpond said piston hody to working con= toot with the wall of said cylinder, and to further enielly compress and radially enpand said piston hody to compensate tor and rods supported in said hody and entending parallel toits axis for a portion of its len h'r or limiting the movement of one of said end plates toward tho-other.

h. In combination o resilient piston body .65 having a central opening through which a en the nut 24 is screwed upon the gaging opposite ends of said piston body,

pressure; and rods supported in said body arallel to its axis, said rods being of a ength less than the length of said body and adapted to limit the maximum pressure ap-- plied on said'fr'esilient piston body by said endplates.

4. In combination:' a resilient piston body having a central opening, the opposite end walls of said bod having an outer concentric' channel defining a eriphcral lip adapted to be forced into wor in contact with, the wall of a cylinder in WhlCl said body oper ates b fluid pressure against the outer wall of sand channel, and an inner concentric channel defining an end hub; end plates eneach plate aving an inner concentric flange cxtendin g inwardly into the companion inner channel of said body to confine the adjacent end hub thereof, and an outer concentric flange at its outer periphery extending in wardly into and engaging the'inner wall of 9; said outer channel; means for moving one of said end plates toward the other to axially compress and radially expand said body into working contact with the Wall of said cylinder, and to further axially compress and radially expand said body to compensate for wear; and rods supported in said resilient piston body parallel to its axis, and of a length less than the length of said body, to limit the movement oi one of said end plates toward the other.

5. in combination: a piston rod; a piston consisting of a resilient piston body having a central opening through which a shaft may extend, the. opposite end walls of said body having formed therein an outer concentric channel defining an outer peripheral lip, and an inner concentric channel defining an end huh; end plates engaging opposite ends oii seid piston ,hody, eech plate having a concentric flange extending inwardly into the compenion inner channel of said body to con line the odjtcent end huhthereoi and a second concentric flange on the outer edge of each end plate extending inwardly into said outer concentric channel and leaving a portion thereof available es a pressure chainleer; means for causing relative movement of said end plates toward each other wherehy the resilient piston body will he axially compressed and. radiall expanded to workin contact with the we I of a cylinder in whic it is adapted to o crate, and to further enially compress on rodielly expand said resilient body to compensate roe lid

f or wear; and

my hand at control means for limiting the pressure applied to said resilient piston body by said last named means.

6. In combination: a piston rod; a piston consisting of a resilient body mounted on said rod; end plates engaging opposite ends of i said piston body; means for causing relative movement of said plates toward each other to axially compress and radially expand said resilient body to working contact with the wall of a cylinder in which it is adapted to operate, and to further axially compress and radially expand said resilient body to compensate for wear; and rods supported in said resilient body to limit the pressure exerted on said body by said end plates.

7. In combination: a piston rod; a piston consisting of a resilient piston body having a central opening through which a shaft may extend, the opposite end walls of said body having formed therein an outer concentric channel defining-an outer peripheral lip, and an inner concentric channel defining an end hub; endplates engaging opposite ends of said piston body with their entire inner surface, each plate having a concentric flange extendinginwardly into the companion inner channel of said body to confine the adjacent end hub thereof, and a second concentric flange on the outer edge of each end plate extending inwardly into said outer concentric channel and leavin a portion thereof available as a pressure 0 amber; means for causing relative movement of said end plates toward each other whereby the resilient piston body will be axially compressed and radially expanded to working contact with the wall of a cylinder in which it is adapted to operate, and to further axially compress and radially expand said resilient body to compensate for wear; and control means for limiting the pressure-applied to said resilient piston body by said last named means.

In testimony whereof, I have hereunto set os Angeles, California, this 30th day of July, 1930. A

s CHARLES LAMB. 

